Optical coherence tomography in an anomalous left circumflex coronary artery with stent thrombosis due to extrinsic compression in hereditary hemorrhagic telangiectasia: a case report.

Background: Anomalous left circumflex coronary artery (ALCx) is a rare condition where the left circumflex artery (LCx) originates from the right sinus of Valsalva (RSV) or the proximal right coronary artery (RCA). In some cases, this condition carries a risk of ischemic manifestations related to its course and anatomical features, potentially leading to extrinsic compression by surrounding structures. Hereditary hemorrhagic telangiectasia (HHT) is characterized by the presence of multiple arteriovenous malformations and hemorrhagic manifestations, but it is also associated with a prothrombotic state. We present the first reported case of acute coronary syndrome (ACS) in which extrinsic compression of the ALCx was documented by intravascular imaging. Case Description: We present the case of a 56-year-old patient with HHT associated with chronic anemia, treated with requiring periodic supplementation, and chronic coronary syndrome due to previous ACS involving the left main and left anterior descending artery, on single antiplatelet therapy. The patient was on the heart transplantation waiting list because of severe left ventricular dysfunction, recurrent heart failure, and ventricular arrhythmias. He was admitted for chest pain and dyspnea and was diagnosed with non-ST-elevation myocardial infarction (non-STEMI) complicated by acute heart failure exacerbation with diffuse crackles on lung examination and B-type natriuretic peptide 1,372 pg/mL. The first percutaneous coronary intervention (PCI) resulted in stent implantation in the ALCx, but the patient subsequently developed early in-stent thrombosis. Optical coherence tomography (OCT) revealed extrinsic compression of the ALCx and the implanted stent, related to the retro-aortic course of the vessel, which likely contributed to the thrombotic mechanism. The patient was discharged on dual antiplatelet therapy (DAPT) with escalation from clopidogrel to the more potent P2Y12 inhibitor ticagrelor despite the underlying hemorrhagic risk. During follow-up, no recurrent stent thrombosis occurred, and the patient underwent heart transplantation nine months later. Conclusions: This case illustrates how ALCx may be associated with extrinsic compression of the vessel and possibly a stent, contributing to the pathogenesis of ischemic events. It also raises the question of the optimal treatment of coronary lesions in ALCx, particularly when thrombotic and hemorrhagic risks coexist.